It is well-known to rigidly secure a prime mover housing to a transmission housing or to form the housing as a single unit. Such prime mover-transmission housing assemblies are commonplace in land vehicles with prime movers of either the combustion engine type or the electric motor type. However, such prior art housing assemblies have had a fixed or unvariable shape, which has required that each housing assembly be designed for a specific vehicle body and chassis or that the body and chassis be designed to accommodate a specific housing assembly.